Re: [Libcg-devel] cgroupstats, plans?

[Balbir Singh <balbir@linux.vnet.ibm.com>]

Paul Menage wrote:
> On Tue, Apr 29, 2008 at 5:20 AM, Dhaval Giani <dhaval@linux.vnet.ibm.com> wrote:
>> Hi Paul,
>>
>>  You had mentioned in http://lkml.org/lkml/2008/4/8/29 about cgroup
>>  binary API for statistics. What is the status wrt to that?
> 
> I've not really had mmore time to work on that since then.
> 
> Assuming people are happy with the basic ideas in that post then I
> guess the important questions to focus on would be:
> 
> - what form should the API description to userspace take? Something
> like the cgroup.api file that I proposed a while ago?
> 
> - how would the user specify and retrieve a specific set of stats?
> should we just dump all stats on each read request, or will that be
> too expensive for some stats?
> 

I would prefer to select the controller from user stats and then dump the stats
from the kernel for that controller using cgroupstats.

>>  We are looking to export statistics using libcg. One of the questions
>>  that comes up is when is a file in the cgroup, a control file (one used
>>  to control the parameters of the subsystem) and when is it a file which
>>  is related to statistics.
> 
> I don't see why some of them can't be both. If a file has a numerical
> value associated with it, is there any reason not to make it available
> via the binary stats API, regardless of whether that value was
> generated by userspace or the kernel?
> 

I agree. I think we need to start pushing the statistics so that we can have a
good set of statistics. I am going to try and do some cgroupstats work and
publish it soon.

-- 
	Warm Regards,
	Balbir Singh
	Linux Technology Center
	IBM, ISTL